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By Alfredo Beltran
This is my version of the Rosette nebula using the Hubble and taken with the ASI071 OSC camera. Telescope was a C925 EdgeHD with Hyperstar lens.
Exposure time: 4hr 50 min in total at unity gain
2hr 00 min (24 x 5 min) Ha
1h 15 min (55 x 5 min) OIII
1hr 35 min (19 x 5 min) SII
This setup is awesome. A few years ago such an image just could’ve been taken with a monochrome ccd.
Slowly dabbling with narrow band and the processing that is becoming more like art than science 🙂
I really am enjoying it though, Imaged this in my red zone back garden last night, it's 10 x 300 secs each of Ha Oiii and Sii ( no darks as they looked weird )
Thanks for looking / feedback.
DSS - Photoshop levels / curves - gradient xterminator - photoshop channel combine as per @swag72 tutorial - photoshop levels to balance colours to my taste - slight noise and star size reduction (Noels tools)
I scrapped all the Oiii and Sii data I previously took during a full moon (about 15 hours worth) and retook it all when the moon was a bit smaller at 76%. Ha was taken during 98% and 67% moon. All the lights were taken on the following nights: 12th, 19th and 20th September 2019.
Integration times, all in 600s subs unbinned:
Ha = 28.33 hours
Oiii= = 5.67 hours
Sii = 5.67 hours
The Ha data is really nice, and unsurprisingly the Oiii and Sii is not as strong (or nice).
I'm missing that (vital) step in my processing routine of getting the Sii and Oiii properly stretched to match the Ha, before combining. I dont really know how to deal with the weaker data properly. Any pointers would be appreciated.
What I do currently:
All the data is loaded into APP into separate channels/sessions.
The data is stacked and registered against the best Ha sub
This produces individual stacks of Ha, Sii and Oiii that are all registered
Each channel is processed with DPP in APP and then saved as a 16bit TIFF
Each is opened in PS
Stars removed with AA and any remnants removed and tidied up
I then open a blank RGB document in PS
I paste Ha into Green, Sii into Red and Oiii into Blue
Adjust the selective colour settings to get 'Hubble palette'
Adjust levels, curves, saturation until looks ok
All the Ha Sii Oiii data is then combined together in a single 'super' stack in APP using quality weighted algorithm to create a 'luminance'
That luminance layer is adjusted using levels, curves, and NC tools such as local contrast enhancement and deep space noise reduction (using masks to apply as required)
The luminance is pasted onto the above colour layer, and incrementally added using gaussian blur
Cropped and saved.
Here it is anyway I haven't intended on any more exposure time for this one, but will consider it, if the expert opinion dictates otherwise!